I actually ended up going with a different pair of Superfeet insoles. I thought the ones I'd tried earlier this year (berry) were the lowest arch they offer, but I was wrong about that. I also found that they were too cushioned under my toes. But I was in a running shoe store looking for new sneakers, and I mentioned that I was looking for insoles for cycling, and the guy working there was very helpful. He had me try the Superfeet black and the carbon insoles. Both have the lowest arch they offer and also have the lowest profile (thinnest). They felt a bit higher than I wanted, but close to being right. I chose the black ones because the carbon are stiffer and less likely to give under my feet. So far I've been mostly happy with them -- they're not quite as comfortable as the LG insoles were before they wore out, but they're better than anything else I tried. Unlike the berry insoles, they haven't caused any alignment problems with my knees.

I haven't seen any Giro insoles, but I will keep an eye out for them and try them if I see them.